Clinical Examples Make It Relevant

Anatomy and Physiology is fundamentally a textbook of the basic science of the human body. However, students always want to know why all the science is relevant to their career aims. Clinical examples and thought questions make it so. Students can see how the science relates to well-known dysfunctions, and why it is important to know the basics. Dysfunctions also provide windows of insight into the basic concepts, such as the insight that cystic fibrosis gives on the importance of membrane ion channels, or that antidepressants give on the synaptic reuptake of neurotransmitters.

There are many tidbits of clinical information that are in this book, but not in others that I have seen. I think that's great! I have learned a thing or two. I also think that the author has tried to choose clinical examples that are commonly dealt with and therefore most useful to the student.

L. Steele, Ivy Tech State College

Pathology Tables

For each organ system, Saladin presents a table that briefly describes several well-known dysfunctions and comprehensively lists the pages where students can find comments on other disorders of that system.

436 Part Two Support and Movement

Smooth muscle exhibits a reaction called the stressrelaxation (or receptive relaxation) response. When stretched, it briefly contracts and resists, but then relaxes. The significance of this response is apparent in the urinary bladder, whose wall consists of three layers of smooth muscle. If the stretched bladder contracted and did not soon relax, it would expel urine almost as soon as it began to fill, thus failing to store the urine until an opportune time.

Remember that skeletal muscle cannot contract very forcefully if it is overstretched. Smooth muscle is not subject to the limitations of this length-tension relationship. It must be able to contract forcefully even when greatly stretched, so that hollow organs such as the stomach and bladder can fill and then expel their contents efficiently. Skeletal muscle must be within 30% of optimum length in order to contract strongly when stimulated. Smooth muscle, by contrast, can be anywhere from half to twice its resting length and still contract powerfully. There are three reasons for this: (1) there are no Z discs, so thick filaments cannot butt against them and stop the contraction; (2) since the thick and thin filaments are not arranged in orderly sarcomeres, stretching of the muscle does not cause a situation where there is too little overlap for cross-bridges to form; and (3) the thick filaments of smooth muscle have myosin heads along their entire length (there is no bare zone), so cross-bridges can form anywhere, not just at the ends. Smooth muscle also exhibits plasticity— the ability to adjust its tension to the degree of stretch. Thus, a hollow organ such as the bladder can be greatly stretched yet not become flabby when it is empty.

The muscular system suffers fewer diseases than any other organ system, but several of its more common dysfunctions are listed in table 11.6. The effects of aging on the muscular system are described on pages 1109-1110.

Before You Go On

Answer the following questions to test your understanding of the preceding section:

Covtracirs Fibromyalgia

Pain, stiffness, and tenderness felt from several hours to a day after strenuous exercise. Associated with microtrauma to the muscles, with disrupted Z discs, myofibrils, and plasma membranes; and with elevated levels of myoglobin, creatine kinase, and lactate dehydrogenase in the blood.

Abnormal muscle shortening not caused by nervous stimulation. Can result from failure of the calcium pump to remove Ca2+ from the sarcoplasm or from contraction of scar tissue, as in burn patients.

Diffuse, chronic muscular pain and tenderness, often associated with sleep disturbances and fatigue; often misdiagnosed as chronic fatigue syndrome. Can be caused by various infectious diseases, physical or emotional trauma, or medications. Most common in women 30 to 50 years old.

A shocklike state following the massive crushing of muscles; associated with high and potentially fatal fever, cardiac irregularities resulting from K+ released from the muscle, and kidney failure resulting from blockage of the renal tubules with myoglobin released by the traumatized muscle. Myoglobinuria (myoglobin in the urine) is a common sign.

Reduction in the size of muscle fibers as a result of nerve damage or muscular inactivity, for example in limbs in a cast and in patients confined to a bed or wheelchair. Muscle strength can be lost at a rate of 3% per day of bed rest.

Figure 10.18 Muscles Acting on the Vertebral Column. Those on the right are deeper than those on the left.

Chapter 10 The Muscular System 351

Semispinalis capitis Semispinalis cervicis

Semispinalis thoracis

Multifidus

Quadratus lumborum

Figure 10.18 Muscles Acting on the Vertebral Column. Those on the right are deeper than those on the left.

erection. In males, the bulbospongiosus (bulbocavernosus)

forms a sheath around the base (bulb) of the penis; it expels semen during ejaculation. In females, it encloses the vagina like a pair of parentheses and tightens on the penis during intercourse. Voluntary contractions of this muscle in both sexes also help void the last few milliliters of urine. The superficial transverse perineus extends from the ischial tuberosities to a strong central tendon of the perineum.

In the middle compartment, the urogenital triangle is spanned by a thin triangular sheet called the urogenital diaphragm. This is composed of a fibrous membrane and two muscles—the deep transverse perineus and the external urethral sphincter (fig. 10.20c, d). The anal triangle contains the external anal sphincter. The deepest compartment, called the pelvic diaphragm, is similar in both sexes. It consists of two muscle pairs shown in figure 10.20e—the levator ani and coccygeus.

Insight 10.3 Clinical Application

Hernias

A hernia is any condition in which"the«v,iscera protrude through a point in the muscular wall of the abdominopelvic cavity. The most common type to require treatment is an inguinal hernia. In the male fetus, each testis descends from the pelvic cavityinto the scrotum by way of a passage called the inguinal canal through trn&muscles of the groin. This canal remains a weak point in the pelvic flooVespecially in infants and children. When pressure rises in the abdominal cavity, it can force part of the intestine or bladder into this canal or even into the scrotum. This also sometimes occurs in men who hold thei\breath while lifting heavy weights. When the diaphragm and abdom cles contract, pressure in the abdominal cavity can soar to 1 pounds per square inch—more than 100 times the no quite sufficient to produce an inguinal hernia, or "rupture." Ingutial

I like Saladin's presentation because I feel an understanding of how medicine and science have changed throughout history is part of becoming a "well educated," not just a "well trained" student.

- R. Pope, Miami-Dade Community College

Clinical Applications

Each chapter has three to five Insight boxes, many of which are clinical in nature. These essays illuminate the clinical relevance of a concept and give insight on disease as it relates to normal structure and function.

The accuracy of information in this text is as good as it gets. Saladin seems to be right on top of every new bit of information that is revealed. What I really like about the Saladin text is that it lets students know when we don't know why something is the way it is. Other texts will try to make the facts fit when they actually don't.

Physiology: The Unity of Companies, 2003 Form and Function, Third Edition

Connective Issues

Interactions Between the RESPIRATORY SYSTEM and Other Organ Systems

• indicates ways in which this system affects other systems

• indicates ways in which other systems affect this one

Connective Issues

The human organ systems do not exist in isolation from each other. Diseases of the circulatory system can lead to failure of the urinary system and aging of the skin can lead to weakening of the skeleton. For each organ system, a page called Connective Issues shows how it affects other systems of the body and is affected by them.

All Systems

The respiratory system serves all other systems by supplying O2, removing CO2, and maintaining acid-ba

Muscular System

^^ Skeletal muscles ventilate lungs, control position of larynx during swallowing, control vocal cords during speech, exercise strongly stimulates respiration because of the CO; generated by active muscles

Circulatory System

Regulates blood pH, thoracic pump aids in venous return, lungs produce blood platelets, production of angiotensin II by lungs is important in control of blood volume and pressure, obstruction of pulmonary circulation leads to right-sided heart

The clinical application approach seems much more consistently and richly in evidence in Saladin.

- D. Plantz, Mohave Community College

858 Part Four Regulation and Maintenance

This section describes the neural mechanisms that regulate pulmonary ventilation. Neurons in the medulla oblongata and pons provide automatic control of unconscious breathing, whereas neurons in the motor cortex of the cerebrum provide voluntary control.

Control Centers in the Brainstem

The medulla oblongata contains inspiratory (I) neurons, which fire during inspiration, and expiratory (E) neurons, which fire during forced expiration (but not during eup-nea). Fibers from these neurons travel down the spinal cord and synapse with lower motor neurons in the cervical to thoracic regions. From here, nerve fibers travel in the phrenic nerves to the diaphragm and intercostal nerves to the intercostal muscles. No pacemaker neurons have been found that are analogous to the autorhythmic cells of the heart, and the exact mechanism for setting the rhythm of respiration remains unknown despite intensive research.

The medulla has two respiratory nuclei (fig. 22.15). One of them, called the inspiratory center, or dorsal respiratory group (DRG), is composed primarily of I neurons, which stimulate the muscles of inspiration. The more frequently they fire, the more motor units are recruited and the more deeply you inhale. If they fire longer than usual, each breath is prolonged and the respiratory rate is slower. When they stop firing, elastic recoil of the lungs and thoracic cage produces passive expiration.

The other nucleus is the expiratory center, or ventral respiratory group (VRG). It has I neurons in its midregion and E neurons at its rostral and caudal ends. It is not involved in eupnea, but its E neurons inhibit the inspira-tory center when deeper expiration is needed. Conversely, the inspiratory center inhibits the expiratory center when an unusually deep inspiration is needed.

The pons regulates ventilation by means of a pneumotaxic center in the upper pons and an apneustic (ap-NEW-stic) center in the lower pons. The role of the apneustic center is still unclear, but it seems to prolong inspiration. The pneumotaxic (NEW-mo-TAX-ic) center sends a continual stream of inhibitory impulses to the inspiratory center of the medulla. When impulse frequency rises, inspiration lasts as little as 0.5 second and the breathing becomes faster and shallower. Conversely, when impulse frequency declines, breathing is slower and deeper, with inspiration lasting as long as 5 seconds.

_Think About It_

Do you think the fibers from the pneumotaxic center produce EPSPs or IPSPs at their synapses in the inspiratory center? Explain.

Figure 22.15 Respiratory Control Centers. Functions of the apneustic center are hypothetical and its connections are therefore indicated by broken lines. As indicated by the plus and minus signs, the apneustic center stimulates the inspiratory center, while the pneumotaxic center inhibits it The inspiratory and expiratory centers inhibit each

Figure 22.15 Respiratory Control Centers. Functions of the apneustic center are hypothetical and its connections are therefore indicated by broken lines. As indicated by the plus and minus signs, the apneustic center stimulates the inspiratory center, while the pneumotaxic center inhibits it The inspiratory and expiratory centers inhibit each

Think About It

Success in health professions requires far more than memorization. More important is your insight and ability to apply what you remember in new cases and problems. Think About It questions, which can be found strategically distributed throughout each chapter, encourage stopping and thinking more deeply about the meaning or broader significance.

Physiology: The Unity of Companies, 2003 Form and Function, Third Edition

Pedagogical Aids Promote Systematic Learning

Saladin structures each chapter around a consistent and unique framework of pedagogic devices. No matter what the subject matter of a chapter, this enables students to develop a consistent learning strategy, making Anatomy and Physiology a superior learning tool.

Insights

Each chapter has from three to six special topic Insight essays on the history behind the science,the evolution behind human form and function, and especially the clinical implications of the basic science. Insight sidebars lend the subject deeper meaning, intriguing perspectives, and career relevance to the student.

Brushing Up

A Brushing Up list at the beginning of the chapter ties chapters together and reminds students that all organ systems are conceptually related to each other.They discourage the habit of forgetting about a chapter after the exam is over. Brushing Up lists are also useful to instructors who present the subject in a different order from the textbook.

The Brain and Cranial Nerves

CHAPTER OUTLINE

CHAPTER

The Brain and Cranial Nerves

CHAPTER OUTLINE

a 524 um 526

• BruinWayes andSlpep 536

• Cerebral lateralization 543

1 Clinical Application:

Meningitis 521

2 Medical History: The A Lobotomy of Phineas G

3 Clinical Application: S Nerve Disorders 556

4 Clinical Application: Ii

Chapter 14 The Brain and Cranial Nerves 529

Chapter 14 The Brain and Cranial Nerves 529

enable the eyes to track and fixate central pattern generators—neuro produce rhythmic signals to the m breathing and swallowing.

Before You Go On

I really like having the objectives listed prior to each section instead of in the beginning of each chapter. In this manner, they are more appropriate for the students and it helps them focus on the issues of importance of that section. The "Think About It" questions are especially nice as it makes the students stop and apply what they have read.

- W. Bircher, San Juan College enable the eyes to track and fixate central pattern generators—neuro produce rhythmic signals to the m breathing and swallowing.

• Cardiovascular control. The reticul includes the cardiac center and vas the medulla oblongata.

• Pain modulation. The reticular fori of the descending analgesic pathwa the earlier description of the reticul

Before You Go On itioned in l tracts. imation has ion through the involved in habitua-

other sequen

>isy city, f through traffic sounds but wake an alarm clock or a crying baby. R that modulate activity of the cere reticular activating system or ext

The Forebrain

Objectives

When you five completed this section, you should be able to

• name the three major components of the diencephalon and describe their locations and functions;

• identify the five lobes of the cerebrum;

• describe the three types of tracts in the cerebral white

• describe the distinctive cell types and histological arrangement of the cerebral cortex; and

• describe the location and functions of the basal nuclei and limbic system.

The forebrain consists of the diencephalon and telen-cephalon. The diencephalon encloses the third ventricle and is the most rostral part of the brainstem. The telen-cephalon develops chiefly into the cerebrum.

Before You Go On

Saladin divides each chapter into short "digestible" segments of about three to five pages each. Each segment ends with a few content review questions, so students can pause to evaluate their understanding of the previous few pages before going on.

Objectives

Each new section of a chapter begins with a list of learning objectives. Students and instructors find this more useful than a single list of objectives at the beginning of a chapter, where few students ever refer back to them as they progress with their reading.

Physiology: The Unity of Companies, 2003 Form and Function, Third Edition

Chapter Review

Briefly restates the key points of the chapter.

Testing Your Recall

Multiple choice and short answer questions allow students to check their knowledge.

True or False

Saladin's True or False questions are more than they appear.They also require the student to explain why the false statements are untrue,thus challenging the student to think more deeply into the material and to appreciate and express subtle points. Answers can be found in the appendix.

The "Testing Your Recall" questions and the "Testing Your Comprehension" questions provide and excellent opportunity for students to review the material in the chapter as a whole, testing not only recall of information, but also the student's ability to apply the information they recall.

- S. Kirkpatrick, Saint Francis University

558 Part Tin*

Chapter Review

Review of Key Concepts

Overview of the Brain (p. 516)

1. The adult brain weighs 1,450 to 1,600 g. It is divided into the cetebtum, -antebellum, and brainstem.

2. The cerebrum and cerebellum exhibit folds called gyti separated by grooves called sulci. The groove between the es is the

gray matter in their surface cortex and deeper nuclei, and white matter deep to the cortex.

4. Embryonic developm progresses through n neural tube stages in 440 Par weeks. The anterior i fourth ventricle, out through foramina in the fourth, into the subarachnoid space around the brain and spinal cord, and finally returns to the blood by way of arachnoid villi.

■■ctpnTusc„b.c. Trueor cerebrospinal fluid (c produced by the epend choroid plexuses and in subarachnoid space aro The CSF of the ventricl the lateral to the third a b. them^stahec 0s. Dlatemehs ate fake, al

c. thick myofilaments ed7i.nThe femur is held tightly in the acetabulum mainly by the round scle ligament.

8. The knuckles are diarthroses.

9. Synovial fluid is secreted by the one bone to another.

Answers in Appendix B

Two Support ed.. tdheinnsem cds..uahlirgehdfcaotilgour.e resistance.

11. The minimum stimulus intensity that will make a muscle contract is called contractiop os of iTohne neurotransmitter that stimulates steletal muscle is than bursae igament lG. Unlike most ligaments, the periodontal ligaments do not attach of i. Synovial

Testing Your Comprehension

Questions that go beyond memorization to require a deeper level of analysis and clinical application. Scenarios from Morbidity and Mortality Weekly Reports and other sources prompt students to apply the chapter's basic science to real-life case histories.

Testing Your Comprehension

1. All second-class levers produce a mechanical advantage greater than 1.0 and all third-class levers produce a mechanical advantage less than 1.0 Explain why.

mechanical advantage. (b) Would this lever produce more force, or less, than the force exerted on it? (c) Which of

3. In order of occurrence, list the joint actions (flexion, pronation, etc.) and the joints where they would occur as you (a) sit down at a table, (b) reach out and pick up an apple, (c) take a bite, and (d) chew it. Assume that you start in anatomical position.

4. Suppose you were dissecting a cat or fetal pig with the task of finding examples of each type of synovial joint. Which type of human synovial joint would not be found in either of those animals? For lack of that joint, what human joint actions would those animals be unable to perform?

5. List the six types of synovial joints and for each one, if possible, identify a joint in the upper limb and a joint in the lower limb that falls into each category. Which of

Answers at the Online Learning Center

Answers to Figure Legend Questions

Thought questions have been added to around five figures per chapter. Answers to these questions are found in this section.

Answers to Figure Legend Questions nt parts of the two pubic

9.15 MA = 1.0. Shifting the fulcrum to the left would increase the MA of this lever, while the lever would remain first-class.

9.18 The stylomandibular ligament is relatively remote from the point

9.24 It is the vertical band of tissue immediately to the right of the medial meniscus.

2. Suppose a levet measures l7 cm ftom effort to fulctum and ll cm ftom tthheesleowsiexrjloiimntbs?have no examples in the three classes of levers could not have these measurements? Explain.

pubic symphysis consists of tilaginous interpubic disc and wone meet.

tbhoeneasd uobmjepcrteesdsitoona. great deal of a wealth of information fully organized and integrated by chapter. You will find s, flashcards, and much more that will complement your learning and understai of

Website Reminder

Located at the end of the Chapter Review is a reminder that additional study questions and other learning activities for anatomy and physiology appear on the Online Learning Center.